“Mad Men” star Jon Hamm is lending his voice to “The Simpsons,” where he plays an FBI investigator whom Hamm likes to think of as “Ron Graper,” he tells Entertainment Tonight.

In the course of the episode, the FBI agent has some frustration with Homer (natch), who is going undercover as a mobster, and “hilarity ensues.”

For Hamm, getting to voice a “Simpsons” character is a bit of a dream come true, since he’s been a fan since the early days of the show.

“I’ve been a fan from the very beginning … I have done the Bartman. I have all of the albums and many of the DVDs, so I’ve been a big fan for a long time,” says Hamm. “This is an amazing experience to be a part of … You don’t have to shave. I was considering not wearing pants. This is fantastic, I could do this again.”

Hamm’s episode of “The Simpsons” airs Sunday (Dec. 12) at 8 p.m. ET/PT on FOX.

Posted by:Andrea Reiher

TV critic by way of law school, Andrea Reiher enjoys everything from highbrow drama to clever comedy to the best reality TV has to offer. Her TV heroes include CJ Cregg, Spencer Hastings, Diane Lockhart, Juliet O'Hara and Buffy Summers. TV words to live by: "I'm a slayer, ask me how."